Photographic process



Nov. 3, 1964 M. c. ROSCOW 3,155,509

PHOTOGRAPHIC PROCESS Filed Sept. 5, 1961 Eel.-

30 Clear Vinyl Polymer 28 L Yellow Dye 26 Clear Vinyl Polymer 24 Magenta Dye Layer Nitro-Ceiluiose Lacquer l L Clear Vinyl Polymer l6 Cyan Dye Layer l4 e)- Separating Material Paper, Glass Or Plastic FIG. 2.

Blue Light Green Light Red Light I I I l l l Red Sensitive (Cy Dy C u Bl maize; B u Bl S 't' Ab b l entities" A we? e Substrate (Film Or Paper) v EFFECT OF LIGHT OF THE PRIMARY COLORS White Light FIG Cyan Dye C r s e Magenta Dye B S Yellow Dye A Substrate Transmits Red Transmits Green THROUGH Fl Llvi AFTER EXPOSURE OF FiG.2.

INVENTOR Morris C Roscow United States Patent Jersey Filed Sept. 5, 1961, Ser. No. 136,1tl7 6 Claims. (Cl. 96-73) This invention relates to a non-silver direct-positive dye-bleach photographic process wherein both full color transparencies and full color prints are produced with images which are sharp and distinct and to the materials from which the color transparencies and color prints are produced.

In copending United States patent applications filed by Robert E. Sprague and others, namely Serial Nos. 47,849, filed August 5, 1960, which issued as United States Patent 3,104,973 on September 24, 1963; and 50,696, filed August 19, 1960, which issued as United States Patent 3,102,027 on August 27, 1963, the disclosures of which are incorporated herein by reference, photosystems are described comprising photolytioally sensitive halogen-containing organic compounds and cyanine and merocyanine dyes which bleach out on exposure to light of a suitable wavelength.

In attempting the practice of the inventions described in the aforesaid patent applications on a semi-commercial or production basis it was found that in many instances the photosensitivity and color separation obtainable with one batch of film was not reproducibly obtainable with succeeding materials prepared and processed in the identical manner from identical source materials.

The principal object of the present invention is to provide means whereby images which are intense, sharp cutting, and in brilliant colors, with good color separation, yielding a very high-quality color rendition are reproducibly obtained and which eliminate the loss in sensitivity and color-separation occasionally experienced in direct-positive non-silver dye-bleach photographic systems of the type described above.

One object of this invention is to provide a non-silver direct-positive dye-bleach photographic system capable of producing full color photographic prints with better color reproduction than has been heretofore obtained in the systems disclosed in the aforementioned patent applications.

Still another object of the invention is to provide a relatively simple photosystem wherein full-color directpositive prints are produced solely by the action of the exposing light without any chemical development.

A still further object of this invention is to provide a process for producing positive transparencies in full color for projection, or for color prints when coated on a white opaque substrate, such as paper.

A further object is to improve the adhesion of the dye layers in the photographic film as compared with that obtained in the aforesaid patent applications.

These and other objects are achieved by utilizing the present photographic system in any of the several alternative modes of practicing the invention described below and illustrated in the accompanying drawings in which:

FIGURE 1 illustrates one tripack embodying the invention;

FIGURE 2 diagrammatically illustrates the effect of exposure of the tripack to light of various colors;

FIGURE 3 schematically shows the resulting direct positive obtained after the exposure of the tripack of FIGURE 1.

As described in the above noted applications, a directpositive full-color print may be obtained by utilization of an integral tripack of three sensitive layers. Each layer comprises a sensitive coating containing a bleach-out dye which is sensitive to radiation of the proper wavelengths, said dye being present with a suitable activating agent and dispersed in a convenient film-former. When the sensitive coating is exposed image-wise to light of the wavelength absorbed by the dye, the dye is bleached in the area struck by the light, with the result that a directpositive image remains in the layer. By proper selection of the dyes an accurate color rendition is obtained by a subtractive process.

For example, a green sensitive layer may be obtained with the process, using a magenta dye, which is, of course, green absorbing, transmitting blue and red freely. When such a film is exposed in a camera, for example, to light reflected from colored objects, the action of green light on this layer is to bleach the magenta dye. It is not, of course, afiected by blue or red light; light of these wavelengths is not absorbed by the sensitive material. What is obtained in this layer, therefore, is a minus-green record which corresponds, for example, with the magenta printer in conventional color printing processes.

Similarly, a blue-sensitive layer, comprising a yellow dye, is bleached on exposure to blue light, giving a minusblue record which corresponds to the yellow printer in conventional printing processes.

Finally, a red-sensitive layer, containing a cyan dye, is bleached by red light, giving a minus-red image corresponding to the cyan printer in color printing processes.

When these three sensitive layers are superimposed in an integral tripack it will be seen that, since all three of the dyes transmit freely in the areas in which they do not absorb, light of a particular color will affect only a single layer. The result of the subtractive reflection of light from a white, opaque substrate on such developed layers is the reflection of light of the same color as that originally exposing the material.

This may be further illustrated by reference to FIG- URES l to 3.

The three-layer integral tripack, depicted in FIGURE 2 consists of three light-sensitive layers superimposed, one on top of the other. The coating nearest the substrate is a blue sensitive yellow dye labelled A, the coating on top of this is a green-sensitive magenta dye labelled B, and the topmost coating is a red-sensitive cyan dye labelled C.

The effect of light of the primary colors, blue, green and red, on such a coating is illustrated by the diagram under the areas marked Blue Light, Green Light, and Red Light. Since the red-sensitive layer C and the green-sensitive layer B transmit blue light freely, no eifect is obtained with blue light until layer A is reached; whereupon the yellow dye is bleached in this area. Therefore, in the area of the film struck by blue light, there remain the cyan layer and the magenta layer. After fixing, which may be accomplished by short heating, if such a developed film is viewed under white light, the cyan layer will absorb red light; the magenta layer will absorb green light; while both the cyan layer and magenta layer will transmit blue freely, as shown in FIGURE 3.

In this way, the result is reflection or transmission of only blue in the area which was originally struck by blue light; in other Words, a direct positive is obtained. Similarly, when green light strikes the three-layer coating, the cyan dye will transmit the green freely while the magenta dye will absorb the green light and be bleached. Since the cyan dye and the yellow dye are still intact and the former will absorb red while the latter will absorb blue, the net reflection or transmission from the bleached layer will be green; again, a direct positive. Finally, in the area struck by red light, the cyan dye will absorb this radiation and be bleached. The greenand blue-sensitive layers will be unaffected. The magenta dye will absorb the green light, the yellow dye will absorb the blue light,

2nd thie net reflection from the combined three layers will e re As indicated above, the three-layer integral tripack depicted in FIGURE 1 comprises paper or other suitable substrate 12 such as glass or plastic, coated with a layer of separating material 14 and then with alternate dye and barrier layers.

Utilizing a system comprising a cyan dye, a magenta dye and a yellow dye it was found that the bleaching behavior of the magenta dye is greatly improved when it is in physical contact with at least one nitrocellulose layer. This is in marked contrast with the cyan and yellow dyes which do not bleach out satisfactorily when in physical contact with a nitrocellulose layer and is evidence that the specific materials are of special importance in this system.

By suitable choice of materials, good separation of colors, with good adhesion and flexibility of coatings is obtained. A preferred embodiment shown in FIGURE 1 was prepared as described in the example which follows.

It is important that the thickness of the dye layer be controlled within certain limits since if th layer is too thin, the dye does not absorb sufiicient light to bleach-out properly and if it is too thick too dense an image is obtained. Wet thickness between about 0.0015 and 0.006 inch, i.e. 1.5 to 6 mils have been found to be particularly useful.

Example 1 A solution was made up consisting of the following:

Butvar B-76 (polyvinyl butyral) grams- 30 Acetone cc 85 Methanol cc 85 Dibutyl phthalate grams 3.0

A layer 14 of the foregoing 0.003 inch thick (wet thickness) was applied to an 80 gram baryta coated glossy paper by means of a Bird film coater. The resulting plastic coated paper was oven dried at 120 F. for two minutes, after which the cyan layer 16 was applied to the barrier layer 14.

The cyan layer 16 was laid down from a solution prepared by dissolving 20 mg. of 1',3-diethylthia-4'-carbocyanine p-toluene sulfonate in a mixture of 6 cc. of acetone and 6 cc. of methanol and then adding 1.5 grams of pentabromethane (C Hl3r and 24 cc. of the previously prepared polyvinyl butyral solution to the dye solution.

The cyan layer 16 was applied with a Bird film coater, in a wet film thickness of 0.003 inch, which was then oven dried to 120 F. for two minutes.

The next layer 18, a clear, colorless composite barrier layer was prepared by mixing 19 cc. of a solution consisting of grams of polyvinyl alcohol (Gelvatol 360, Shawinigan) in 90 cc. of water with 1 cc. of a solution consisting of 1.5 cc. of 38% ammonium hydroxide and 30 grams of a vinyl acetate copolymer (Gelva C-5 V-16R, Shawinigan) in 200 cc. of water, and adding about 1 cc. of water to lower the viscosity.

This layer, the preceding layers, and all succeeding layers were laid down by the Bird film applicator, in a wet thickness of 0.003 inch and then oven dried for between 1 and 4 minutes as indicated.

The drying time for the vinyl polymer layer 18 was 4 minutes, after which a layer 22 of a nitrocellulose lacquer was deposited on the dried layer 18.

The nitrocellulose lacquer was prepared by mixing the following:

Hercules Nitrocellulose RS (5-6 sec.) (35% alcohol wet) "grams" 39 Hercules Nitrocellulose (-20 sec.) (35% alcohol wet) "grams" 150 Ethanol cc 20 Dibutyl phthalate grams 18 Isopropyl acetate cc.. 710 Isopropyl alcohol cc 194 -Xs may differ from the remaining Xs.

When the above had completely dissolved, the lacquer was diluted with isopropyl acetate (5 grams lacquer to 1 cc. of isopropyl acetate) to reduce the viscosity to a workable system.

After a layer 22 of the nitrocellulose lacquer was laid down by the Bird applicator and oven dried for 1 minute at 120 F., a. layer 24 containing the magenta dye and the sensitizer for the magenta dye was laid down in similar fashion.

The magenta layer 24 was deposited from a solution formulated by dissolving 15 mg. of l,3-dimethyloxa-2- carbocyanine p-toluene sulfonate in 6 cc. of methanol and 6 cc. of acetone, and then adding thereto 6 grams of pen tabromethane (C HBr and 24 cc. of the above described polyvinyl butyral solution.

After oven drying layer 24 for 2 minutes at 120 F., a clear colorless composite barrier layer 26 having the same composition as layer 18 (deposited on the cyan layer) was laid down on the dried magenta containing layer, and then oven dried at 120 F. for 4 minutes.

A solution of yellow dye was prepared by dissolving 15 mg. of 5 (3-ethyl-2(3H)-benzoxazolylidene)-ethylidene]- 3-phenyl-2-phenylimino-4-thiazolidone in 10 cc. of toluene and 2 cc. of dimethyl formamide. To this, 6 grams of pcntabrornethane (C HBr and 24 cc. of a solution consisting of the following:

Butvar B76 (polyvinyl butyral) grams 30 Toluene cc.. 162 Dimethyl tormamide cc 8 Dibutyl phthalate grams 3 A layer 0.003 inch thick (wet) 28 of the resulting solution was laid down as before and oven dried at 120 F. for 2 minutes.

A final layer 30 of the tripack applied to the dried yellow dye layer 28, was composed of the clear colorless polyvinyl alcohol, polyvinyl acetate-copolymer containing solution previously applied to both the cyan and magenta layers. After drying this for 4 minutes the film was ready for use.

The resulting film was exposed to illumination from a 500 watt projection lamp, passed through either a colored subject to be duplicated or through various combinations of color filters. Exposure times of 5-25 minutes at 3-5X magnification yielded satisfactory prints.

Fixing may be accomplished by treatment with suitable chemicals to leach out or destroy the activity of the polyhalogenated sensitizer.

Instead of pentabromethane, other polyhalogenated compounds of the type disclosed in the aforementioned copending patent applications could be used. These may be represented by the general formula RCX wherein R represents a monovalent radical selected from the group consisting of H; Cl; Br; alkyl; substituted alkyl, particularly halogen substituted alkyl; aryl and substituted aryl; and each X represents a halogen selected from the group consisting of Cl, Br and I, and one or more of the In preferred sensitizers, the X represents Br and compounds having three or more bromine atoms attached to a single carbon atom are particularly preferred, e.g. CBr C HBr C H CBr and the like.

As described in the above noted applications between about 1 and 10,000 parts by weight of halogen containing activating agent should be present for each part by weight of dye in the dye layers.

The coating was exposed under a series of Wratten filters (cyan, magenta, yellow, blue, green, and red) to the light from the Bell and Howell SOD-watt projector at 5 magnification, for a period of approximately minutes. This resulted in clean, white bleachout in the clear areas, and excellent color reproductions of each filter. A print of an average color transparency at a 3X enlargement may be made, using this material, with an exposure of about 20-25 minutes.

Alternative constituents for the clear colorless resinous component of the substrate, barrier, and top layers are polyvinyl butyral, polyvinyl alcohol, modified polyvinyl acetate, polyvinyl chloride, acrylic ester, and ethyl cellulose, and other polymer containing only C, H, O and halogen and which do not adversely affect the color reproductions obtained with the bleachout dyes of the type exemplified. It will be understood also that other bleachout dyes may be substituted for the specific cyan, magenta and yellow dyes disclosed in the example without departing from intended scope of the invention which is not intended to be limited except as required by the appended claims.

I claim:

1. A photosensitive element consisting of a solid support member; a clear, colorless barrier layer deposited on said support from a solution; a cyan layer coated on said clear, colorless layer, said cyan layer having been deposited as a thin layer from a solution comprising a solvent in which there are dissolved a binder, a bleachable cyan dye and an organic halogen-containing compound selected from the group consisting of alkyl and aralkyl compounds in which at least three halogen atoms are attached to a single carbon atom and in which the halogen atoms are selected from the group consisting of Cl, Br and I, from which coating the solvent has been eliminated; at first photoinsensitive layer of clear, colorless polyvinyl resin on said cyan layer; a layer of nitrocellulose lacquer on said layer of polyvinyl resin; a magenta layer coated on said nitrocellulose lacquer layer, said magenta layer having been deposited as a thin layer from a solution comprising a solvent in which there are dissolved a binder, a

bleachable magenta dye and an organic halogen-containing compound selected from the group consisting of alkyl and aralkyl compounds in which at least three halogen atoms are attached to a single carbon atom and in which the halogen atoms are selected from the group consisting of Cl, Br and I from which layer the solvent has been eliminated; a second photoinsensitive layer of clear, colorless polyvinyl resin deposited on said magenta layer; a yellow dye layer coated on said second clear polyvinyl resin layer, said yellow dye layer having been deposited as a thin layer from a solution comprising a solvent in which there are dissolved a binder, a bleachable yellow dye, and an organic halogen compound selected from the group consisting of alkyl and aralkyl compounds in which at least three halogen atoms are attached to a single carbon atom and in which the halogen atoms are selected from the group consisting of Cl, Br and I and superimposed on said yellow dye layer, a layer of clear, colorless polyvinyl resin, there being between about 1 and 10,000 parts by weight of organic halogen containing compound in each or" said dye layers for each part of dye therein, by weight, each of said dye layers being deposited as a wet film having a wet thickness of between about 0.0015 and 0.006 inch and each of said non-dye layers being of such thickness as to prevent diffusion of the constituents from the dye layer on one side of said non-dye layer to the dye layer on the opposite side of said non-dye layer.

2. The photosensitive element of claim 1 wherein the organic halogen containing compound is selected from the group consisting of carbon tetrabromide, pentabromo ethane and benzotribromide.

3. The photosensitive element of claim 1 wherein the binder is polyvinylbutyral, and the bleach-out dyes are sensitized by pentabromethane.

4. The photosensitive element of claim 1 wherein the base is paper.

5. The method of producing a direct-positive non-silver colored reproduction of a colored image which comprises preparing the photosensitive element of claim 1 and projecting the colored image to be reproduced onto said element.

6. A photographic element for a non-silver direct positive dye bleach process in which a colored image is produced solely and directly as a result of the exposure of said element to the projection of a colored image thereon, said element consisting of the structure defined in claim 1 wherein the halogen containing compounds are hydrocarbon compounds containing at least three bromine atoms attached to a single carbon atom.

References Cited in the file of this patent UNITED STATES PATENTS 821,200 Szczepanilr May 22, 1906 1,517,049 Christensen Nov. 25, 1924 2,054,390 Rust et al Sept. 15, 1936 2,391,198 Seymour Dec. 18, 1945 2,983,606 Rogers May 9, 1961 3,043,692 Haas et al July 10, 1962 3,104,973 Sprague et a1. Sept. 24, 1963 

1. A PHOTOSENSITIVE ELEMENT CONSISTING OF A SOLID SUPPORT MEMBER; A CLEAR, COLORLESS BARRIER LAYER DEPOSITED ON SAID SUPPORT FROM A SOLUTION; A CYAN LAYER COATED ON SAID CLEAR, COLORLESS LAYER, SAID CYAN LAYER HAVING BEEN DEPOSITED AS A THIN LAYER FROM A SOLUTION COMPRISING A SOLVENT IN WHICH THERE ARE DISSOLVED A BINDER, A BELACHABLE CYAN DYE AND AN ORGANIC HALOGEN-CONTAINING COMPOUND SELECTED FROM THE GROUP CONSISTING OF ALKYL AND ARALKYL COMPOUNDS IN WHICH AT LEAST THREE HALOGEN ATOMS ARE ATTACHED TO A SINGLE CARBON ATOM AND IN WHICH THE HALOGEN ATOMS ARE SELECTED FROM THE GROUP CONSISTING OF CL, BR AND I, FROM WHICH COATING THE SOLVENT HAS BEEN ELIMINATED; A FIRST PHOTOINSEENSITIVE LAYER OF CLEAR, COLORLESS POLYVINYL RSIN ON SAID CYAN LAYER; A LAYER OF NITROCELLULOSE LACQUER ON SAID LAYER OF POLYVINYL RESIN; A MAGENTA LAYER COATED ON SAID NITROCELLULOSE LACQUER LAYER, SAID MAGENTA LAYER HAVING BEEN DEPOSITED AS A THIN LAYER FROM A SOLUTION COMPRISING A SOLVENT IN WHICH THERE ARE DISSOLVED A BINDER, A BLEACHABLE MAGENTA DYE AND AN ORGANIC HALOGEN-CONTAINING COMPOUND SELECTED FROM THE GROUP CONSISTING OF ALKYL AND ARALKYL COMPOUNDS IN WHICH AT LEAST THREE HALOGEN ATOMS ARE ATTACHED TO A SINGLE CARBON ATOM AND IN WHICH THE HALOGEN ATOMS ARE SELECTED FROM THE GROUP CONSISTING OF CI, BR AND I FROM WHICH LAYER THE SOLVENT HAS BEEN ELIMINATED; A SECOND PHOTOINSENSITIVE LAYER OF CLEAR, COLORLESS POLYVINYL RESIN DEPOSITED ON SAID MAGENTA LAYER; A YELLOW DYE LAYER COATED ON SAID SECOND CLEAR POLYVINYL RESIN LAYER, SAID YELLOW DYE LAYER HAVING BEEN DEPOSITED AS A THIN LAYER FROM A SOLUTION COMPRISING A SOLVENT IN WHICH THERE ARE DISSOLVED A BINDER, A BLEACHABLE YELLOW DYE, AND AN ORGANIC HALOGEN COMPOUND SSELECTED FROM THE GROUP CONSISTING OF ALKYL AND ARALKYL COMPOUNDS IN WHICH AT LEAST THREE HALOGEN ATOMS ARE ATTACHED TO A SINGLE CARBON ATOM AND IN WHICH THE HALOGEN ATOMS ARE SELECTED FROM THE GROUP CONSISTING OF CI, BR AND I AND SUPERIMPOSED ON SAID YELLOW DYE LAYER, A LAYER OF CLEAR, COLORLESS POLYVINYL RESIN, THERE BEING BETWEEN ABOUT 1 AND 10,000 PARTS BY WEIGHT OF ORGANIC HALOGEN CONTAINING COMPOUNDS IN EACH OF SAID DYE LAYERS FOR EACH PART OF DYE THEREIN, BY W EIGHT, EACH OF SAID DYE LAYERS BEING DEPOSITED AS A WET FILM HAVING A WET THICKNESS OF BETWEEN ABOUT 0.00015 AND 0.0006 INCH AND EACH OF SAID NON-DYE LAYERS BEING OF SUCH THICKNESS AS TO PREVENT DIFFUSION OF THE CONSTITUENTS FROM THE DYE LAYER ON ONE SIDE OF SAID NON-DYE LAYER TO THE DYE LAYER ON THE OPPOSISTE SIDE OF SAID NON-DYE LAYER. 